1. Field of the Invention
This invention relates generally to storage networks and, more specifically, to a network device on a storage network that coordinates segmentation and reconstruction of a file having a size larger than a native processing capability of a commodity file server into several data chunks within its capability.
2. Description of the Related Art
In a computer network, NAS (Network Attached Storage) file servers connected directly to the network provide an inexpensive and easily configurable solution for a storage network. These NAS file servers are self-sufficient because they contain file systems that allow interoperability with clients running any operating system and communication using open protocols. For example, a Unix-based client can use the NFS (Network File System) protocol by Sun Microsystems, Inc. of Santa Clara, Calif. and a Windows-based client can use CIFS (Common Internet File System) by Microsoft Corp. of Redmond, Wash. to access the same files on a NAS file server. Thus, NAS file servers provide true universal file access.
By contrast, more expensive and powerful SAN (Storage Area Network) file servers use resources connected by Fibre Channel on a back-end, or a dedicated network. A SAN file system is part of the operating system or an application running on the client. But heterogeneous client operating systems may require additional copies of each file to be stored on the storage network to ensure compatibility on the SAN file server. Additionally, communication between clients and file servers on a SAN use proprietary protocols and thus are typically provided by a common vendor. As a result, NAS file servers are preferred when price and ease of use are major considerations. However, the benefits of NAS storage networks over SAN storage networks also have drawbacks.
One drawback with NAS file servers is that there is no centralized control. Accordingly, each client must maintain communication channels between each of the NFS file servers separately. When NAS file servers are either added or removed from the storage network, each client must mount or unmount directories for the associated storage resources as appropriate. This is particularly inefficient when there are changes in hardware, but not in the particular files available on the network, such as when a failing NAS file server is swapped out for an identically configured back-up NAS file server.
Another drawback of NAS file servers is that as commodity devices, they are typically outfitted with 32-bit legacy software and/or hardware that is not capable of processing files greater than 2-GB. For example 32-bit processors and NFS version 2 NAS protocol are limited to 32-bit data capability. Problematically, many data files are larger than 2-GB such as video files and back-up files. Other files start out less than 2-GB, but subsequently grow beyond this size. Additionally, heterogeneous NAS storage networks can contain both enterprise file servers that support 64-bit data and commodity file servers that support 32-bit data that cannot be used to replicate or migrate large data files between each other.
Therefore, what is needed is a robust network device to provide transparency for clients of decentralized file servers such as NAS file servers. Furthermore, the network device should transparently coordinate large file storage on a commodity file server and process access request to the large file.